JP3041333B2 - Data communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication system for modulating and demodulating time-series digital data using a high-speed data modem.

[0002]

2. Description of the Related Art Telecommunications network systems are undergoing major changes toward the advanced information society in the 21st century. Nowadays, telecommunication has become an important social infrastructure and is essential for the development and efficiency of personal life and socio-economics. In particular, in the field of telephone communication, the latest digital communication technology and the advance of computer technology have been adopted, and mobile phones and pagers (P
ager) and the like have achieved remarkable development.

FIG. 12 shows an example of a conventional route for sending a message to a pager. The area where the pager service is provided is divided into several zones 10. A transmitting station 12 for transmitting a radio wave to a pager is provided corresponding to each zone 10. The message to the pager is first sent to the telephone office 14. This message is transmitted from the telephone station 14 to each transmitting station 12 via the relay cable 16, and each transmitting station 12 transmits a radio wave to the corresponding zone 10. Thus, a system is constructed in which the pager can receive radio waves regardless of the zone 10.

As can be easily inferred from FIG. 6, the distance from the telephone station 14 to each transmitting station 12 is not constant.
That is, the length of the relay cable 16 differs for each transmitting station 12. Therefore, in general, the transmission time of a message from the telephone station 14 to each transmitting station is different from each other. As a result, if the telephone station transmits a message to each transmitting station 12 at the same time, each radio wave transmitted by each transmitting station 12 has a time difference from each other.

If the pager is located near the boundary of the zone 10, radio waves from a plurality of transmitting stations will be received at the same time. If the time difference between these radio waves increases, stable reception is no longer possible. Therefore, it is specified that the time difference between the radio waves must be within 10 μs.

Conventionally, in order to make this time difference within 10 μs, when transmitting from the telephone station 14 to each transmitting station 12, a time delay is added according to the other transmitting station, and a radio wave output from each transmitting station 12 is added. The time difference was gone. In other words, the closer the transmitting station 12 is, the longer the time delay, and
Was sent to. Thereby, the timings transmitted from the respective transmitting stations 12 can be aligned. The amount of time delay added by the central office 14 is manually adjusted.
When a new device is introduced, or when a relay cable 1
The adjustment of the amount of the delay time is usually performed when the laying of 6 is performed.

In recent years, not only mobile phones and pagers,
With the increase in facsimile machines and network communication, it is a social urgent need to increase the communication capacity of information communication. Therefore, in recent information communication, a high-speed modem called a so-called high-speed data modem device has been used in order to improve a transmission speed.

[0008] This high-speed data modem device has a 9600b
Extremely high-speed communication of about ps can be performed. Incidentally, the transmission quality of a general analog communication channel is not so high, and the quality varies depending on the distance.
Therefore, this high-speed data modem device inspects the quality of the communication path prior to communication, and automatically changes the transmission speed, constants of the equalization circuit and the like from the result. If an error occurs during the actual communication, or if an instantaneous interruption occurs, training etc. is automatically performed when communication is restored, effective recovery from the error and its preventive measures Has been realized.

As described above, in order to make the best use of the characteristics of the communication path, the transmission speed and timing of the high-speed data modem apparatus greatly depend on the transmission quality of the communication path.

[0010] Since the high-speed data modem device has such characteristics, it is very difficult to apply the high-speed data modem device to the purpose of transmitting a message to a mobile phone or a pager.

Because, as described above, when a message is transmitted from each transmitting station in the form of a radio wave, the time difference between the radio waves from each transmitting station 12 must be within 10 μs. When a high-speed data modem is used, communication is automatically restarted in response to a momentary interruption of the communication path, as described above, so it has been extremely difficult to keep the time difference between radio waves within 10 μs.

[0012]

Since the conventional device is configured as described above, it is very difficult to transmit a message to each transmitting station 12 using a high-speed data modem device in order to transmit the message to the pager. was difficult.

However, with the increase in the number of pagers and the like, there is a problem that the transmission speed must be improved by all means. Therefore, a data communication system that uses a high-speed data modem device and has a constant transmission delay time to each transmitting station has been desired in society.

[0014]

According to the present invention, first, reference bit data generated by a reference bit data generator of a transmitter is inserted into time-series digital data at regular intervals. The inserted data is modulated by the high-speed data modem device and transmitted to the analog communication path. On the other hand, the reference sine wave generator generates a sine wave having the same cycle as the cycle of the reference bit data, and this sine wave is synthesized by the reference sine wave synthesizer with the modulation signal of the output of the high-speed data modem device and is applied to the analog communication path. Sent out.

The reference sine wave separator of the receiver separates the reference sine wave and the modulation signal from the signal received from the analog communication path. The separated modulated signal is demodulated by the receiving high-speed data modem device to obtain a demodulated signal. The reference bit data separator separates the demodulated signal into reference bit data and time-series digital data. A phase difference between the reference sine wave and the reference bit data is detected by a phase comparator, and a time delay unit delays the time-series digital data based on the phase difference information and outputs the time-series digital data to the outside.

[0016]

The receiving side detects the phase difference between the reference bit data modulated and demodulated by the high-speed data modem device together with the time-series digital data and the reference sine wave transmitted independently of the high-speed data modem device. The modulation / demodulation time in the high-speed data modem device can be calculated.
Therefore, if a delay time is added according to a change in the modulation / demodulation time, the total delay time from input to output can be kept constant.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of a communication system according to the present invention. This communication system includes a transmitting device 20, a plurality of receiving devices 22, and a communication path 24 connecting them. The telephone station transmits a message to each transmitting station using the transmitting device 20, and each transmitting station receives the message using the receiving device 22 and transmits a radio wave to a pager. Since the receiving devices of each transmitting station perform the same operation, FIG. 1 shows only one receiving device and omits the other receiving devices.

The message to be transmitted is first transmitted by the transmitting device 2
It is input to the reference bit data inserter 26 within 0. The message into which the reference bit data has been inserted by the reference bit data inserter 26 is transmitted to the high-speed data modem 28 on the transmitting side.
Undergo modulation. The modulation output of the high-speed data modem device and the reference sine wave are combined in the reference sine wave combiner 30 and transmitted to the communication path 24. Here, the reference signal generator 32 generates the reference bit data and the reference sine wave. These reference signals are supplied to the reference bit data inserter 26 and the reference sine wave synthesizer 30, respectively.

The signal from the communication path 24 is input to a reference sine wave separator 34 in the receiving device 22. The reference sine wave separator 34 separates the reference sine wave from the received signal,
6 is output. The remaining received signal from which the reference sine wave has been removed is output to the high-speed data modem device 38 on the receiving side.
The signal demodulated by the high-speed data modem device 38 on the receiving side is output to the reference bit data separator 40. The reference bit data separator 40 extracts and extracts reference bit data from the output of the high-speed data modem device 38 on the receiving side. The signal from which the reference bit data has been removed is input to the shift register 42. The reference bit data from the reference bit data separator 40 is compared in phase by the phase comparator 36 with the separated reference sine wave. The phase difference information as a result of the comparison is output from the phase comparator 36 to the shift register 42. The shift register 42 outputs a message by delaying the signal from the reference bit data separator 40 based on the phase difference information.

Hereinafter, the transmitting device 20 and the receiving device 22 are sequentially described.
Will be described in detail. FIG. 2 shows a detailed block circuit diagram of the transmission device 20, and FIG. 3 shows a detailed block circuit diagram of the reception device 22.

The transmission device Figure 2 is a detailed block circuit diagram of the transmitter 20. The reference bit data inserter 26 to which the message is input is a serial / parallel converter 5 composed of a shift register.
0 and a latch 52 for holding reference bit data from the reference signal generator 32. The message output of the serial / parallel converter 50 and the reference bit data output of the latch 52 are connected in parallel to the high-speed data modem 28.
Is being entered. As a result, the reference bit data is inserted in the message. The parallel signal of the message and the reference bit data is modulated by the high-speed data modem device 28 and output to the data combiner 30 as serial data.

The reference signal generator 32 includes an oscillator 54 for oscillating a rectangular wave and a low-pass filter 56. The oscillator oscillates a 400 Hz rectangular wave, which is input to the reference bit data inserter 26 as reference bit data, and is held in a latch 52 therein. 400H
The rectangular wave of z is converted into a reference sine wave by the low-pass filter 56. The low-pass filter 56 is constituted by a digital filter or the like, and the phase can maintain a fixed relationship with the 400 Hz rectangular wave.

The data synthesizer 30 is a signal adder such as an analog adder. The data synthesizer 30 adds the modulation output from the high-speed data modem device 28 and the reference sine wave from the reference signal generator 32 in an analog manner, and sends the result to the communication path 24.

The modulation output from the high-speed data modem unit 28 has a frequency component of about 500 Hz or more, while the reference sine wave from the reference signal generator 32 has a frequency of 400 Hz.
Hz. As a result, as described later, the receiving apparatus can separate the modulated signal and the reference sine wave from the signal on the communication path using the low-pass filter and the high-pass filter.

[0026] Receiving Apparatus FIG. 3 is a detailed block circuit diagram of the receiving apparatus 22. Reference sine wave separator 3 to which the received signal from communication channel 24 is input
4 is a high-pass filter 60 for removing the reference sine wave;
A low-pass filter 62 for extracting only the reference sine wave. The high-pass filter 60 is a filter that extracts only a signal of 500 Hz or higher, and can effectively remove a reference sine wave of 400 Hz. The low-pass filter 62 is a filter that extracts only a signal of 400 Hz or less, and can extract only a 400 Hz reference sine wave. The output of the high-pass filter 60 is input to the high-speed data modem device 38 on the receiving side, and the reference sine wave of 400 Hz, which is the output of the low-pass filter 62, is input to the phase comparator 36.

The above-mentioned modulated signal is demodulated by the high-speed data modem device 38 and input to the reference bit data separator 40 as parallel data. The reference bit data separator 40 inputs the data other than the reference bit data to the parallel / serial converter 64 in the reference bit data separator 40 in order to use the data for reproducing the message. The reference bit data is output to the phase comparator 36 as it is. Thus, the reference bit data is separated. The output of the demodulated message from the parallel-to-serial converter 64 is input to the shift register 42 to delay the time.

4 which is the output of the low-pass filter 62
The 00 Hz reference sine wave is input to a comparator 66 in the phase comparator 36. The phase comparator 36 includes a comparator 66, a phase difference detector 68, and a delay amount calculator 70.
And The comparator 66 determines the polarity of the sine wave to binarize the sine wave, that is, converts the sine wave into a rectangular wave. The determination of polarity is achieved by comparing with "0" volts.

The phase difference between the output of the comparator 66 and the reference bit data from the reference bit data separator 40 is detected by a phase difference detector 68. Phase difference detector 68
Is a counter for measuring time, and outputs the phase difference of the signal as time. This time is written as a phase difference time ΔT, which is output to the delay amount calculator 70.

The delay amount calculator 70 calculates the phase difference time ΔT
The difference T−ΔT between the reference sine wave and the period T of the reference sine wave is calculated and output to the shift register 42.

The shift register 42 outputs the serial data of the demodulated message, which is the output of the reference bit data separator 40, after delaying it by the time T-ΔT. Next , the operation of this embodiment will be described with reference to FIG. FIG. 4 is a time chart showing typical signals from transmission to reception.

In this embodiment, a message to be communicated is divided into 8 bits, and these 8 bits are called one frame. Each frame is separated by a frame bit "F".

In this embodiment, the period T of the reference bit data is set to a time of two frames. That is, the reference bit data is inserted one bit per frame,
The value repeats “0” and “1” for each frame. The transmission data in FIG. 4 shows a state where the reference bit data is inserted, and the position of the reference bit data is represented by “R”. An example of the value is shown in FIG. 4 as reference bit data, and as described above, the value is a value that repeats “0” and “1” for each frame.

The signal which repeats "0" and "1" every frame is the signal itself output from the oscillator 54 of the reference signal generator 32. This signal is applied to a low-pass filter 5
6 is a reference sine wave, and the waveform of the reference sine wave is shown in the figure. In this embodiment, the reference sine wave and the reference bit data have a frequency of 400 Hz.
Is set to That is, their period T is 2.5 milliseconds.

The modulated signal from the transmitting high-speed data modem device 38 and the reference sine wave are combined in an analog manner and sent out to the communication path 24.

In the receiving device, the reference sine wave separator 3
The modulated signal and the reference sine wave are separated by the high-pass filter 60 and the low-pass filter 62 in FIG. The separated modulated signal is input to a high-speed data modem on the receiving side and demodulated. The state of the demodulated data is shown in FIG. A value obtained by extracting “R”, that is, the value of the reference bit data from the demodulated data in FIG. 4 is shown in the lower part of the demodulated data in the figure.

On the other hand, the separated reference sine wave phase comparator 3
6 and is converted into a binary signal, that is, a rectangular wave. This converted signal is shown below the reference sine wave in the figure. The phase difference time between the binary signal (rectangular wave) and the extracted reference bit data is measured as ΔT by the phase difference detector 68.

This ΔT is nothing but the modulation and demodulation time of the high-speed data modem device on the transmitting side and the high-speed data modem device on the receiving side. By measuring this ΔT, the modulation and demodulation time of the high-speed data modem device can be calculated. Can be measured.
The difference between ΔT and the cycle of the reference bit data is calculated by the delay amount calculator 70 and sent to the shift register 42.

When the demodulated data from the receiving high-speed data modem device is converted to serial data by the parallel / serial converter 64, the reference bit data is ignored.
As a result, it is possible to remove the reference bit data. The demodulated message from which the reference bit data has been removed is shown in FIG.

Finally, the demodulated message is sent to the shift register 4
2 and is delayed by T-ΔT time to become the final output.

As described above, the message to be communicated is delayed by ΔT time by the high-speed data modem device, and by T−ΔT time by the shift register 42, that is, the total T time. That is, according to the present embodiment, the modulation / demodulation time by the high-speed data modem device is measured, and a time delay is applied in accordance therewith, so that the delay amount of the message can always be T time.

For example, when the modulation / demodulation time becomes longer, the delay time by the shift register 42 becomes shorter accordingly, so that the total delay time is kept at a constant value. FIG. 5 shows an example in which the modulation / demodulation time is longer than the example shown in FIG. By comparing FIGS. 4 and 5, it can be seen that the total delay time is always constant.

[0043]

As described above, according to the present invention,
Two types of reference signals (reference bit data and reference sine wave)
One of them was modulated and demodulated by a high-speed data modem, and the other was sent directly to the communication channel. By measuring the phase difference with the receiver, the modulation and demodulation time could be known.
Because a final time delay is applied based on the modulation / demodulation time, the modulation / demodulation of high-speed data
Even if the demodulation time fluctuates, the time delay between transmission and reception can be kept constant.

Thus, according to the present invention, the time delay between the telephone station and the transmitting station can be made constant, and as a result, the service of the pager can be broadened.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a communication system according to the present invention.

FIG. 2 is a block circuit diagram showing one embodiment of a transmission device of the communication system according to the present invention.

FIG. 3 is a block circuit diagram showing one embodiment of a receiving device of the communication system according to the present invention.

FIG. 4 is a time chart showing representative signals in one embodiment of the communication system according to the present invention.

FIG. 5 is a time chart showing a representative signal in one embodiment of the communication system according to the present invention, and is a time chart showing a case where the modulation / demodulation time is longer than the case shown in FIG.

FIG. 6 is an explanatory diagram for explaining a mechanism for sending a message to a pager by a conventional communication system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Zone 12 Transmitting station 14 Telephone station 16 Relay cable 20 Transmitting device 22 Receiving device 24 Communication channel 26 Reference bit data inserter 28 High speed data modem device 30 Reference sine wave synthesizer 32 Reference signal generator 34 Reference sine wave separator 36 Phase Comparator 38 High-speed data modem device 40 Reference bit data separator 42 Shift register 50 Serial-parallel converter 52 Latch 54 Oscillator 56 Low-pass filter 60 High-pass filter 62 Low-pass filter 64 Parallel-serial converter 66 Comparator 68 Phase difference detector 70 Delay Quantity calculator

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masanori Matsumoto 7-3-16 Kikuna, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Inside Oi Electric Co., Ltd. (56) References JP-A-2-151135 (JP, A) 2-192327 (JP, A) JP-A-61-62244 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 7/24-7/26 102 H04Q 7/00-7 / 38

Claims (1)

(57) [Claims] 1. A transmitting device for modulating time-series digital data using a high-speed data modem device on a transmitting side and transmitting the modulated signal to an analog communication channel; and receiving the modulated signal from the analog communication channel. A demodulator using a high-speed data modem device on the side, and a receiving device for decoding the time-series digital data, wherein the transmitting device generates reference bit data every predetermined period. A generator, a reference bit data inserter that inserts the reference bit data into the time-series digital data every fixed period and outputs the time-series digital data to the high-speed data modem device on the transmission side, and has a same period as the reference bit data. A reference sine wave generator for generating a sine wave, a modulation signal output from the high-speed data modem device on the transmission side, and the reference sine wave. A reference sine wave synthesizer that combines and sends the modulated signal to the analog communication path, wherein the reception device separates a reception signal received from the analog communication path into the reference sine wave and a modulation signal, and A reference sine wave separator for outputting to the high-speed data modem device on the receiving side; and a reference bit data separating device for separating the demodulated signal output from the high-speed data modem device on the receiving side into the time-series digital data and the reference bit data. A phase comparator that measures a phase difference between the separated reference sine wave and the separated reference bit data. Based on the phase difference information output by the phase comparator, the time-series digital data And a time delay device for delaying the time.